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Secondary structure [4] [5] α-Helices Cylindrical spiral ribbons, with ribbon plane approximately following plane of peptides. β-Strands Arrows with thickness, about one-quarter as thick as they are wide, showing direction and twist of the strand from amino to carboxy end. β-sheets are seen as unified because neighboring strands twist in unison.
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers – specifically polypeptides – formed from sequences of amino acids, which are the monomers of the polymer. A single amino acid monomer may also be called a residue, which indicates a repeating unit of a polymer.
Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule of protein, DNA, or RNA, and that is important to its function.The structure of these molecules may be considered at any of several length scales ranging from the level of individual atoms to the relationships among entire protein subunits.
Folded, 3-D structure of ribonuclease A. Anfinsen's dogma, also known as the thermodynamic hypothesis, is a postulate in molecular biology.It states that, at least for a small globular protein in its standard physiological environment, the native structure is determined only by the protein's amino acid sequence. [1]
All proteins should be classified to structural families to understand their evolutionary relationships. Structural comparisons are best achieved at the domain level. For this reason many algorithms have been developed to automatically assign domains in proteins with known 3D structure (see § Domain definition from structural co-ordinates).
Protein function depends on 3-D structure and these 3-D structures are more highly conserved than sequences. Thus, the high-throughput structure determination methods of structural genomics have the potential to inform our understanding of protein functions. This also has potential implications for drug discovery and protein engineering. [2]
Proteins are often synthesized in an inactive precursor form; typically, an N-terminal or C-terminal segment blocks the active site of the protein, inhibiting its function. The protein is activated by cleaving off the inhibitory peptide. Some proteins even have the power to cleave themselves.
Protein–protein interaction prediction is a field combining bioinformatics and structural biology in an attempt to identify and catalog physical interactions between pairs or groups of proteins. Understanding protein–protein interactions is important for the investigation of intracellular signaling pathways, modelling of protein complex ...